A Linkage Between the L-Band Amplitude Scintillations and the Steepest TEC Gradients at the Boundaries of the Equatorial Ionization Anomaly Crests

GPS derived total electron content (TEC) mapping with coupled amplitude scintillation data at the GPS L1 frequency (1.575 GHz) are used to study their specific relationships. We used data collected from the Brazilian GPS receiver network and a time-dependent inversion algorithm to create the 2-D images with the coupled TEC and scintillation measurements. We have found that the scintillation events are strongly correlated with the regions in the ionosphere where the steepest TEC gradients are observed (at the boundaries of the equatorial ionization anomaly crests). In order to study such relations, we carried out 3-D numerical simulations of equatorial plasma bubbles that include the dynamics parallel and perpendicular to the magnetic field. The simulations show that the large ionospheric density gradients at the boundaries of the anomaly are probably responsible for the observed large TEC fluctuations and the L-band amplitude scintillations.